The present invention relates to an electronic apparatus which is equipped with an ultrasonic motor and which is operated by output pulses corresponding to the environment or the states of the components of the electronic apparatus or to the environment around the components of the electronic apparatus.
FIG. 26 is a block diagram of the prior art electronic apparatus equipped with an ultrasonic motor. As shown in FIG. 26, an oscillator circuit 202 is powered by a power supply 201 and delivers a given output signal. A frequency division circuit 203 receives the output signal from the oscillator circuit 202 and divides the frequency. A timing signal generating circuit 204 receives the output signal from the frequency division circuit 203 and delivers a given timing signal. An output pulse-generating circuit 230 receives the output signal from the timing signal generating circuit 204, receives the output signal from a driving pulse-generating circuit 206, and delivers output pulses. A piezoelectric vibrator-driving circuit 208 receives the output signal from the output pulse-generating circuit 230 and delivers an output signal which produces ultrasonic vibration that activates the ultrasonic motor.
The piezoelectric vibrator-driving circuit 208 applies a given high frequency voltage to a piezoelectric vibrator 144. Ultrasonic vibration is induced in vibrating member 143. A moving member 142 is rotated or otherwise operated. A pressure-regulating spring 141 applies a given pressure to the vibrating member 143 and to the moving member 142.
FIG. 27 is a cross-sectional view of the prior art ultrasonic motor. As shown in FIG. 27, a central shaft 146 is rigidly fixed to an anchor block 147. The vibrating member 143 is firmly mounted to the central shaft 146. The piezoelectric vibrator 144 is adhesively bonded to the underside of the vibrating member 143. The piezoelectric vibrator 144 is polarized into a given shape. A lead wire 145 connects the electrode pattern on the piezoelectric vibrator 144 with a circuit for driving the piezoelectric vibrator.
The vibrating member 143 has a plurality of comb-like projections 143a. The moving member 142 is brought into contact with the comb-like projections 143a of the vibrating member 143 via friction member 148. The moving member 142 is mounted to the central shaft 146 so as to be rotatable. The pressure-regulating spring 141 presses the moving member 142 against the comb-like projections 143a of the vibrating member 143. A given high frequency voltage is applied to the piezoelectric vibrator 144 from the piezoelectric vibrator-driving circuit. Ultrasonic vibration is induced in the vibrating member 143. The moving member 142 is rotated via the frictional force of the friction member 148.
FIG. 28 is a perspective view of the prior art traveling-wave type ultrasonic motor. A plurality of comb-like projections 123a are equally spaced from each other on a vibrating member 123. A moving member 122 is brought into contact with the comb-like projections 123a to the vibrating member 123 via friction member. A pressure-regulating spring 121 presses the moving member 122 against the comb-like projections 123a of the vibrating member 123. A plurality of high frequency voltages which are out of phase with each other are applied to a piezoelectric vibrator 124 from a piezoelectric vibrator-driving circuit. The moving member 122 is rotated by traveling wave produced in the vibrating member 123. This prior art structure is disclosed in, for example, Patent Laid-Open No. JP-A-177874/1989.
FIG. 29 is a perspective view of the prior are standing wave type ultrasonic motor. A vibrating body 133 is provided with a plurality of comb-like projections 133a corresponding to the wave number of a standing wave. A moving member 132 is brought into contact with the comb-like projections 133a of the vibrating member 133 via friction member. A pressure-regulating spring 131 the moving member 132 against the comb-like projections 133a of the vibrating member 133. On high frequency voltage is applied to a piezoelectric vibrator 134 from a piezoelectric vibrator-driving circuit. The moving member 132 is rotated by the standing wave induced in the vibrating member 133. This prior art structure is disclosed in, for example, Patent Laid-Open No. JP-A-107472/1988.
The conventional electric apparatus equipped with an ultrasonic motor have the following problems.
(1) Since given output pulses are delivered irrespective of rotation of the ultrasonic motor, it is difficult to reduce the electric power consumed.
(2) Since the operation is not controlled according to the environment of the components of the ultrasonic motor or according to the environment around the components, it is difficult to stabilize the performance in operation.
(3) It is difficult to precisely control the angular position of the ultrasonic motor.